The invention relates to a pipe member having an infeed point for an additive or having a plurality of such infeed points and having a static mixing element. The invention also relates to a conduit with the pipe member of the invention and to uses of the pipe member. The additives are mixed into a flowing low viscosity fluid by means of the static mixing element. The static mixing element consists of a pair of vanes and a third vane which is arranged cross-wise with respect to the vane pair. In this respect, a vane is understood to be a plate-like body which is flat or which can also be lightly curved, which has an elongate design and which extends between a base and a narrow end.
The pipe member in accordance with the invention can in particular be a ring which can be clamped between flanges of conduit parts disposed upstream and downstream. Such an intermediate flange ring for the additional dosing and mixing of an additive (or of a plurality of additives) into a fluid stream is known, for example, from U.S. Pat. No. 5,839,828. The additive is fed into the inner space of the ring via connections and is there mixed into the fluid stream under the influence of a diaphragm which induces a vortex. For an improvement of the mixing quality, it has been proposed (European application No. 01810359.8xe2x80x94not pre-published) to use instead of the diaphragm, which has a particular symmetry, a mixing element with crossing vanes, the mixing element not having the symmetry present in the diaphragm. Furthermore, the improved device should be made in the form of a ring dosing device in which the mixing in of the additive is carried out while using a plurality of spot-wise infeed points, with these infeed points being positioned at an annular passage around the mixing element.
It is an object of the invention to provide a pipe member for mixing in one or more additives into a flowing low viscosity fluid, with the pipe member including a mixing element with crossing vanes and with the additive feed taking place in a manner which is simpler to carry out than with the annular dosing device and without compromises in the mixing quality.
The pipe member having an infeed point for an additive or having a plurality of such infeed points includes a pipe wall and a static mixing element. The infeed points are provided for introducing the additives into a flowing low viscosity fluid. The static mixing element consists of a pair of vanes and a third vane. The vane pair, which forms a restriction deflecting the flow of the fluid, is formed with substantially mirror symmetry with respect to a central plane extending in the direction of the flow. The third vane is arranged in a crossing manner with respect to the vane pair and in a lying manner in the region of the central plane. It has a rear side with respect to the flow which extends from a base at the pipe wall to a downstream end. Each infeed point is arranged at the rear side of the third vane.
In accordance with the invention, the infeed point is arranged at the rear side of the third vane. It has surprisingly been found that with such an arrangement, which is very simple in design thanks to a single infeed point, a mixing quality results which is substantially better than expected. This mixing quality is better than with the annular dosing device of more complex designs in which the additivexe2x80x94in the expectation of a better mixing qualityxe2x80x94is fed into the mixing space through an annular passage and a plurality of nozzle passages, with the same mixing element being installed in this mixing space as in the more favorable arrangement.
The invention will be described in the following with reference to the drawings.